Information playback systems frequently utilize a stylus for reading signals from the surface of an information record, typically a plastic disc, that contains stored video and audio information. In some systems the information record has a fine spiral groove to guide the tip of a stylus that contains a thin electrode. In these systems, the stylus tip is made of a material having sufficient hardness to withstand the abrasion caused from tracking the groove. Materials which possess such hardness, for example diamond, generally have a crystallographic structure which presents surfaces exhibiting different qualities depending upon which crystallographic planes the surfaces are oriented along. Consequently, in manufacturing styli from these crystallographic materials for use in video disc playback systems, it is important to known and maintain the tip orientation during the various processing steps in order to achieve uniform styli of high quality.
The stylus tip is typically fabricated from a relatively small stone, e.g., a diamond stone, which is supported in a holder as a workpiece during the processing steps. The orientation of the stylus tip is usually controlled during processing by a positioning ring attached to the holder. The holder is adapted to rotate the tip, with respect to the positioning ring, about an axis, so that a particular surface of the tip may be oriented along a desired plane. The present invention provides a novel method and apparatus for aligning a particular surface of the tip with respect to the positioning ring within an accuracy of about .+-.1/2.degree..